Phosphite ester

In organic chemistry, a phosphite ester or organophosphite usually refers to an organophosphorous compound with the formula P(OR)3.

For alkyl alcohols the displaced chloride ion can attack the phosphite, causing dealkylation to give a dialkylphosphite and an organochlorine compound.

[1][2] The overall reaction is as follows: Alternatively, when the alcoholysis is conducted in the presence of proton acceptors (typically an amine base), one obtains the C3-symmetric trialkyl derivatives:[3] A base is not essential when using aromatic alcohols such as phenols, as they are not susceptible to attack by chloride, however it does catalyse the esterification reaction and is therefore often included.

Aryl phosphite esters may not undergo these reactions and hence are commonly used as stabilizers in halogen-bearing polymers such as PVC.

They exhibit tautomerism, however, the equilibrium overwhelmingly favours the right-hand (phosphonate-like) form:[11][12] The P-H bond is the site of high reactivity in these compounds (for example in the Atherton–Todd reaction and Hirao coupling), whereas in tri-organophosphites the lone pair on phosphorus is the site of high reactivity.

The general structure of a phosphite ester showing the lone pairs on the P
Tris(2,4-di-tert-butylphenyl)phosphite , a widely used stabilizer in polymers
Autoxidation of a keto steroid with oxygen to the hydroperoxide (not depicted) followed by reduction with triethylphosphite to the alcohol
BiPhePhos is representative diphosphite ligand used in homogeneous catalysis. [ 9 ] [ 10 ]
Structure of a diethylphosphite.